Low levels of vitamin D have again been linked with reduced survival rates in patients with heart failure.

The study, conducted at the University Medical Center, Groningen, in the Netherlands, also suggested that low levels of vitamin D are associated with activation of the Renin Angiotensin System (RAS – a pivotal regulatory system in heart failure) and an altered cytokine profile.

“By showing that vitamin D is an independent predictor, we hoped to prove that it is a contributory factor to, rather than peripheral to, the development and prognosis of heart failure. With this new information, we then hope to provide better insight into the pathophysiology of heart failure,” said said researcher Licette Liu.

The study is said to be the first conducted in a large cohort of patients recruited due to hospitalisation for heart failure, in which the role of vitamin D has been determined, along with the roles of plasma renin activity and cytokines.

Vitamin D concentration was assessed in plasma samples from 548 heart failure patients. According the researchers, patients with lower concentrations had a higher risk of death or required re-hospitalisation, whereas patients with higher concentrations had lower survival risks for these endpoints.

“Further, significant correlations between vitamin D, and Plasma Renin Activity and C-Reactive Protein were found. These correlations suggest that the association between vitamin D and the prognosis in heart failure may be explained by activation of the RAS and an altered cytokine profile.”

Although the observational study was limited as bystander and indirect effects of variables could not be discounted, researchers urged heat patients to ensure adequate vitamin D intake.

“This study provides compelling evidence that a high vitamin D status is associated with improved survival in heart failure patients. Until an intervention study has been designed and completed, it seems that we should advise patients with heart failure to maintain appropriate vitamin D levels by taking supplements, by eating oily fish or eggs, or simply by exposure to sunlight,” said Liu.

Science builds up

The findings, which were presented at the European Society of Cardiology (ESC) Congress 2010 at the end of August, follows similar research linking low blood levels of vitamin D to higher mortality.

A study published last year in the journal Clinical Endocrinology reported that low blood levels of the sunshine vitamin are associated with increased risk of all-cause mortality, and mortality from heart disease.
Out of 614 participants, 51 deaths were recorded in a six-year follow-up period, 20 of which were due to cardiovascular health. People with the lowest average vitamin D levels (30.6 nanomoles per litre) were found to be at a 124 and 378 per cent increased risk of all-cause mortality and cardiovascular mortality, respectively.

Another study published in Nutrition Research and led by Richard Semba from the Johns Hopkins University looked at vitamin D levels in the form of 25- hydroxyvitamin D (25(OH)D), in 714 community-dwelling women, aged between 70 and 79 years.

Semba and his co-workers noted that several biologic mechanisms could explain a causal relationship between vitamin D deficiency and mortality, with the vitamin’s active form (1,25-dihydroxyvitamin D) linked to a range of effects including control of inflammatory compounds, regulating immune health and blood pressure, or reducing arterial hardening.
Prior to this, similar findings were published in the Archives of Internal Medicine from a study using data from 13,331 men and women participating in the Third National Health and Nutritional Examination Survey (NHANES III).

Vitamin D deficiency has also been linked to osteopenia, osteoporosis, muscle weakness, fractures, common cancers, autoimmune diseases and infectious diseases There is also some evidence that the vitamin may reduce the incidence of several types of cancer and type-1 diabetes.